Our "Potluck 2010" column generated more response than any other column in 2010. In it, a driver was put out of service because he had a blood alcohol concentration of .03, eight hours after drinking a glass of wine.

We have written about it before, but there still seem to be many questions surrounding alcohol use and alcohol violations with respect to commercial vehicle operations. We can't cover all of the issues in this column. But if you will look in the subject index of your federal regulations handbook under "alcohol," you will find all the information you need to know. Here are some of the questions we've received.

Q.I'm a little confused on the advice you gave the driver about the alcohol incident. I think we both know if he only has one glass of wine the night before, this wouldn't be an issue. What bothers me is how enforcement has whittled away at the .04 BAC (blood alcohol concentration) limit. Is it .04 or now do we have "measurable" limits?

A. That is a great question. The answer to this question comes from multiple references in the regulations in reference to alcohol. The main reference is section 392.5; in a nutshell, a driver is not to use, or be under the influence of alcohol:

Within four hours before going on duty;

With a measurable amount of alcohol concentration; and

With a .04 or greater BAC, which is also the DUI standard for a CDL holder while operating a commercial vehicle.

In reference to item No. 2, a reading of 0.02 on a DOT alcohol test is the lowest concentration that is considered a "positive" result. So the measurable amount would be a .02-.039 BAC, and anything above that would be DUI territory in a CMV.

Q.My point is law enforcement has so many ways to "interpret" the law. Shouldn't the advice have been to stand up and fight for your rights or be one of the herd going to the slaughterhouse with our tails between our legs? If he refused the breathalyzer, would he have lost his license?

A. Another great question. As frustrating as things can be on the road, you need to remember that driving is a privilege and not a fundamental right. With the implied consent laws, you generally do not want to refuse to take a breathalyzer test. If you refer to Section 383.51, it is a one-year disqualification of your CDL if you refuse to take a breathalyzer, whether in a CMV or non-CMV, even if you would have passed it.

Q.I must say that it confirms me in my practice of only drinking, if at all, when I am home and have several days off ahead of me. Still, it's frustrating to picture this person's predicament. My understanding is that it is perfectly legal to drink, say, a glass of wine, rest eight (or even six) hours, then drive. Why did you not address this issue?

A. The best course of action is your practice of drinking while at home or off-duty and certainly not in your CMV.

Yes, it is legal to drink alcohol. But the important lesson to take from the Q&A is that there are severe penalties and pitfalls for the uninitiated out on the road. For example, the DOT interpretation of Section 392.5, prohibiting the possession of un-manifested alcohol in a CMV, says that it doesn't apply if a driver is off-duty or using a vehicle for personal reasons. However, if you still possess the alcohol the next day when you go on-duty, you are now in violation of Section 392.5 for being in possession of alcohol while on-duty or operating a CMV. LL